There are known self-contained demolition charges which comprise built-in fuzes with a primer a delay mechanism and a booster charge, so designed that upon release of an arming lever the fuze is activated and detonated after a preset delay sufficient for the operator to withdraw into safety. However, cases of premature detonation do happen with fatal consequences to the operator(s). Such premature detonation may be, for example due to malfunctioning by which the primer ignites spontaneously even though the arming lever has not been released, or alternatively may be due to direct activation of the detonator by unintentional percussions. In either case the detonator is prematurely activated whereby the booster charge is prematurely ignited which in turn causes premature explosion of the entire demolition charge with obvious fatal consequences. It is thus the object of the present invention to provide an improved fuze for demolition charges that is safe against premature activation of the detonator.